Philadelphia Undergoes Major Green Infrastructure Overhaul to Manage Combined Sewer…

The city of Philadelphia operates a combined sewer system where rainwater and domestic sewage flow together in pipes. This system, which serves 60 percent of the city, can become overwhelmed during heavy rain, leading to combined sewer overflows into local rivers and streams. The city has been pursuing a green infrastructure strategy to address this issue, which officials say has been a concern since the early 2000s.

The infrastructure challenge involves the city's location between the Delaware and Schuylkill rivers. The city has been exploring alternatives to massive underground storage caverns, which were estimated to cost as much as nine billion dollars. The current program is a 25-year investment aimed at resolving this long-standing environmental issue.